Typically, snow is removed from pavement by a truck that is provided with a snowplow having a moldboard that is mounted on the front end of the truck. Various arrangements are known for raising and lowering the moldboard of the snow plow as desired and for changing the angle that the moldboard of the snow plow makes with the longitudinal center axis of the truck, and therefore with respect to the longitudinal axis of the lane of pavement being cleared.
The moldboard of the snow plow may be selectively raised and lowered so that the plow truck may be driven with the lowermost edge of the moldboard either in contact (for conducting a plowing operation) or out of contact with the road, such as when the truck is being driven over pavement which has already been cleared of snow. Also, the snow plow is typically arranged to enable the angle of the plow with respect to the truck to be changed so that the snow plow can be used to divert snow to the left or to the right of the truck or used to push snow directly in front of the truck such as when clearing a driveway or parking lot.
Various wing plows and other attachments are also known in the snow removal art which effectively extend the width of the lane that can be plowed by a single truck in a single pass. However, such wing plows are typically mounted at one side of the truck and present significant problems for the operation of the truck in plowing situations. For example, the use of a wing plow produces significant torque and disruptive forces on the truck frame and the suspension of the snowplow truck. Also, the maximum practical length of a wing plow is relatively small and does not readily permit additional lanes of pavement to be cleared of snow during a single pass of the snowplow vehicle.
Accordingly, the need remains for a snowplow arrangement in which a relatively wide strip of pavement may be cleared of snow in a single pass of a snowplow vehicle, preferably without requiring an additional operator and without requiring an additional vehicle.
Accordingly, the present invention provides a snowplow which is towed by a vehicle such as a municipal truck and which can travel at relatively high speeds on highways and on roads while occupying generally only one lane of pavement or less. When it is desired to plow the pavement, the towed snowplow can then be quickly deployed to either the left or the right of the vehicle, depending upon the configuration of the towed snowplow, to plow either to the left or to the right of the towing vehicle. In this way, the towing vehicle together with the towed snowplow can simultaneously clear several adjacent lanes of a multilane roadway system or highway, as well as pavement shoulders, airport runways or other wide areas. The towed snowplow is configured to not require an additional operator for the towed snowplow and so the multiple lanes of pavement may be cleared of snow in a single pass of the combined towing vehicle and towed snowplow using only one truck and one operator.
It is a particular advantage of the preferred embodiments of the present invention that the towed snowplow can be transported from location to location like a trailer that is towed behind the motorized vehicle, such as a municipal truck, and then the towed snowplow can be deployed to the right (or left depending upon the configuration of the towed snowplow) using steering axles or pivoting axles to cause the trailer to swing out to one side of the towing truck. The towed snowplow automatically deflects or slides in the event that the towed snowplow blade(s) or moldboard(s) strike an obstacle, without incurring major damage to either the towed snowplow or to the towing vehicle.
In the preferred embodiments of the towed snowplow according to the present invention, roads and highways may be more quickly cleared of snow and other winter precipitation which improves safety by reducing accidents and by reducing the number of stranded vehicles and travelers. Because the towed snowplow does not require a second operator in the towing vehicle, the preferred embodiments of the present invention improve efficiency and production for snow clearing operations and reduce the need for additional numbers of snowplow trucks and operators.
The preferred embodiments of the present invention enable snow plow operations to also plow soft shoulders of roadways without placing the snowplow truck physically onto the shoulder of the pavement. In addition, plowing operations in mountainous situations are relatively safer because the snowplow truck may maintain a safer distance from the outside edge of the pavement and thereby more easily avoid inadvertently driving off of the roadway.
The wide plowing capability of the preferred embodiments of the present invention enables the towing vehicle and towed snowplow to plow irregular cross sections more quickly and efficiently as well as providing an arrangement to cut, blow or squeegee pavement by using two cutting edges.
Specifically, the towed snowplows according to the preferred embodiments of the present invention are much safer to use than conventional front and side (wing) plows which may be mounted on the front, the middle, or the rear of snowplow trucks. These conventional side (wing) plows can present major dynamic loads on the plow, as well as on the push frames and the truck frames, on the chassis of the snowplow, as well as on the axles and wheels of the snowplow truck.
The towed snowplow according to the present invention can strike relatively large or even permanent obstacles and deflect without causing great stress to the towing vehicle.
The preferred embodiments of the present invention can be used to plow more safely at relatively higher speeds than most or all conventionally known snowplows, while being stable, when compared to side or wing plows, which often tend to hop, lope, bounce or porpoise. In this way, the towed snowplow according to the present invention is suitable for use at relatively higher speeds while plowing on interstate highways as well as on high speed expressways.
Side or wing plows also cause significant loading on their deployed side while simultaneously causing the other side of the snowplow truck to become relatively much lighter. If a side or wing plow is relatively large, it can often overload the tires of the snowplow truck especially on the side of the truck where the side or wing plow is deployed. Overloading of the tires and the suspension of a snowplow truck presents a safety hazard and is likewise illegal in many states. The towed snowplow according to the preferred embodiments of the present invention does not overload the front steering axles of the towing vehicle as can occur with side or wing plows.
It is also common in some situations to initially plow the pavement or highway surface so as to remove snow. Subsequently, the snowplow truck is used to plow the shoulders of the roadway. This practice places the snowplow truck (typically heavily loaded with salt or sand or gravel) upon the dirt, sod or improved shoulder of the roadway. However, the heavily loaded trucks can make ruts in soft shoulders or can damage seal coats or other improved shoulders. The towed snowplow of the present invention can be used to plow highway shoulders without placing the loaded towing truck physically onto the shoulder, thus reducing shoulder damage.
The preferred embodiments of the present invention also enable the towed snowplow to be moved from one site to the next (while not in a deployed or plowing configuration) while located within a single conventional lane of traffic and without encroaching outside of the lane like wing plows and other conventionally known plowing systems.
The towed snowplow according to the present invention may have one or more moldboards totaling generally from 10 feet to 40 feet or more which may be towed directly behind the towing vehicle from a storage location such as a maintenance shop to the pavement to be plowed.
In the preferred embodiments of the present invention, the towed snowplow is steered from the driver's seat of the towing vehicle which allows the driver or operator of the snowplow truck to selectively deploy and retract the towed snowplow from the transport position (directly behind the towed vehicle) to the plowing position (diagonally behind the vehicle) in 200′ or less.
In addition to moving the towed snowplow between the transport position and the deployed position, the steering of the towed snowplow can also be used to cause the plow to favor the left or right side during transport or to steer and negotiate the towed snowplow around hard turns. Typically during relatively gradual curves, such as are common on major highways and interstate road systems, the towed snowplow will remain in either the transport position or in the deployed position without additional steering.
During a plowing operation, the driver or operator of the vehicle can easily vary the plowing width of the towed snowplow such as to accommodate turn lanes or temporary increases or decreases in pavement widths. When in the deployed position, the towed snowplow of the present invention is stable at any desired angle with respect to the towing vehicle.
The towed snowplow according to the present invention can be easily steered around obstacles and then returned to its plowing or deployed position. Accordingly, the towing truck may remain in one lane of pavement without deviating and the operator may use the towed snowplow to plow around an obstacle such as a parked vehicle located on the highway shoulder. After passing the obstacle, the operator may rapidly return the towed snowplow to resume the plowing of one or more additional lanes of pavement. In addition, the towed snowplow is able to pivot around or easily pass over obstructions such as raised pavement markers, joints and other obstacles.
The towed snowplow can easily hook to conventional dump trucks, especially to municipal snowplow trucks, which have pintle hitches. Front and side plows typically require the installation of additional hardware that is attached or otherwise hooked to the truck frames or to bumpers. The towed snowplow of the present invention, however, can use the standard hitches normally used by trucks for pulling pups or trailers along with the standard hydraulic and electrical hookups conventionally provided on such trucks for use with towed trailers.